The present.invention relates generally to devices for storing data. More specifically, the present invention relates to disk drives that are hermetically sealed and the methods for providing such seals.
Disk drives are widely used in computers and data processing systems for storing information. These disk drives commonly use magnetic storage disks to store data in digital form. In order to obtain higher storage capacities, disk drives have evolved from utilizing a single rotating storage disk to utilizing a plurality of spaced apart rotating storage disks.
Each storage disk typically includes a data storage surface on each side of the storage disk. These storage surfaces are divided into a plurality of narrow, annular, concentric regions of different radii, commonly referred to as xe2x80x9ctracks.xe2x80x9d Typically, an actuator assembly is used for precisely positioning a data transducer proximate the appropriate track on the storage disk to transfer information to and from the storage disk.
The need for increased storage capacity and compact construction of the disk drive has led to the use of smaller disks having increased track density, i.e., more tracks per inch. With these systems, the accurate and stable positioning of the data transducer proximate the appropriate track is critical to the accurate transfer and/or retrieval of information from the rotating storage disks.
As is well known in the art, the rotating storage disks are excited by internal and external vibration of the disk drive. This vibration causes axial motion in the rotating disks. Unfortunately, some of this axial motion is transferred to the data transducers. This can lead to errors in the transfer of data caused by the inaccurate positioning of the data transducer relative to the tracks on the rotating disks. This is commonly referred to as xe2x80x9ctrack mis-registration (TMR).xe2x80x9d
Moreover, the need to rapidly access information has led to disk drives having storage disks which are rotated at ever increasing speeds. Presently, disk drives having disks that rotate at about 7,200 RPM are currently available. However, high speed disk drives that rotate at 10,000 RPM or more RPM are presently being designed. At these high speeds, a significant portion of the internal vibration is caused by turbulent excitation of the head/disk assembly. Thus, the increased rotational speed of the storage disks often results in increased levels of vibration of the rotating disks and increased occurrences of TMR. Additionally, the higher RPMs generate more aerodynamic drag on the disks and increase drive power consumption.
It is known that alternate atmospheres surrounding the head/disk assembly (HDA) can reduce the magnitude of the aforementioned aerodynamic drag and turbulent excitation. For example, the use of helium is disclosed in U.S. Pat. No. 5,454,157. However, conventional disk drives use relatively permeable gaskets and seals in combination with a controlled diffusion filtered path to replenish the HDA as it gradually leaks outward. This type of conventional design prevents the use of alternate HDA atmospheres such as helium. In addition, known methods for hermetically sealing the HDA have yet to be successfully implemented.
Therefore, there exists a need for a hermetically sealed disk drive assembly that overcomes the drawbacks of the prior art.
The present invention is directed to a hermetically sealed data storage device and the methods for hermetically sealing a data storage device e.g. a disk drive. According to a first embodiment of the present invention, a disk drive assembly is hermetically encased within a metallic can. The metallic can comprises a top housing and a bottom housing. Each housing includes a sealing flange extending around its periphery. After the disk drive assembly is securely placed into the bottom housing, the top and bottom housings are mated together and sealed together by forming a seam seal with the seal flanges.
According to a second embodiment, a metallic gasket having a C-shaped cross-sectional area is implemented to hermetically seal a disk drive assembly. The C-seal includes a base layer and a plating layer, with the length of the seal extending the periphery of the disk drive base, similarly to conventional elastomer gaskets. After the disk drive cover is placed over the disk drive base and C-seal, the cover is clamped, thus compressing the C-seal. The resulting compression forces the plating layer to fill surface asperities in the area of disk drive cover and base that contact the C-seal.
In a third embodiment, an epoxy seam is provided between the disk drive cover and base to hermetically seal the head/disk assembly. An O-ring type gasket is utilized to isolate the epoxy from the HDA.